MySQL query to find users who don't want email

[TerryMason]

I ended up getting this code to work. I can't say that I really understand it though

	//  Get Members
	$members = $db->query_read("
		SELECT user.email, user.userid, user.username, user.options " . iif((!empty($vbulletin->options['c_news_letter_field'])),",userfield." . $vbulletin->options['c_news_letter_field'] . "") . "
		FROM " . TABLE_PREFIX . "user AS user
		" . iif((!empty($vbulletin->options['c_news_letter_field'])),"LEFT JOIN " . TABLE_PREFIX . "userfield AS userfield ON (userfield.userid = user.userid)") . "
		WHERE user.userid >= " . $vbulletin->GPC['startat'] . " 	
	        " . iif((!empty($vbulletin->options['c_news_letter_field']))," AND (userfield." . $vbulletin->options[c_news_letter_field] . " = '" . $vbulletin->options[c_news_letter_field_yes] . "' OR userfield." . $vbulletin->options[c_news_letter_field] . " = '')") . "  

		" . iif(!$vbulletin->GPC['user']['adminemail'], " AND (options & " . $vbulletin->bf_misc_useroptions['adminemail'] . ")") . "

		" . iif((!empty($vbulletin->GPC['usergroups'])), "AND user.usergroupid IN ('" . implode("','",$c_news_letter_filter_usergroups) . "')") . "
		ORDER BY user.userid ASC
		LIMIT " . $vbulletin->GPC['perpage']
	);

this was the line that did the heavy lifting:

" . iif(!$vbulletin->GPC['user']['adminemail'], " AND (options & " . $vbulletin->bf_misc_useroptions['adminemail'] . ")") . "

Do you guys see any problems with this code?